snow tire question

[Tihol Tiholov]

A bit late with this.
Heat cycling may be a fine theory and we can beat our keyboards to death.
My BTDT includes 2 Firestones, bought new, on the front and 2 ancient Yoko
732 or similar on the rear with a lot of tread.  Vastly different tread
patterns, car (Typ 89) has the usual excellent traction and tracks better
than with the previous Yoko 600 Gardex on all 4 wheels - bought new, little
wear, 1 or 2 couple swapped with new ones under warranty.  It used to pull
to the right with the Gardex on.